The Assay Services Core will make available to participating investigators the resources of the University of Michigan Research Assay Support Laboratory (RASL), a reference laboratory for nicotine/cotinine HPLC analysis. Projects 1,2, and 3 will make extensive use of the nicotine/cotinine assay, for venous and (in the case of Project 1) arterial samples. Project 2 will also include assays for plasma cortisol, caffeine, and methylphenidate. Project 3 requires the preparation and purification of a nicotine bitartrate solution for administration via an intranasal nicotine aerosol delivery device. PCR-based DNA analyses to determine twin zygosity will be provided for Projects 3 and 4. Plasma samples for cotinine analyses to characterize nicotine intake from usual smoking will be analyzed for all smokers, and blood samples will be obtained from all subjects and stored for subsequent DNA analyses to determine genetic influences on nicotine dependence.